In general, as coated tools, throw-away tips which are detachably attached to the tip end portion of an insert holder to be used for turning or planing a work material such as various kinds of steel and cast iron, drills or miniature drills used for drilling or the like of the work material, end mills used for facing, grooving, shoulder milling, and the like of the work material, solid hobs and pinion cutters used for gear cutting of the work material into tooth shapes, and the like are known.
In addition, various suggestions have hitherto been made for the purpose of improving the cutting performance of coated tools.
For example, as described in Japanese Patent No. 3781374, a coated tool is suggested in which the surface of a tool body made of tungsten carbide (hereinafter, referred to as WC)-based cemented carbide, titanium carbonitride (hereinafter, referred to as TiCN)-based cermet, or the like is coated with one or more hard layers having a cubic structure composed of a metal component primarily containing Cr, Al, and Si and at least one element selected from C, N, O, and B such that the fracturing resistance and wear resistance are improved.
In addition, Japanese Unexamined Patent Application, First Publication No. 2004-34186 suggests a coated tool in which the surface of a tool body is coated with at least one layer of coating containing Si and B by containing, as metallic elements, elements selected from one or more of groups 4a, 5a, and 6a in the periodic table and Al and the element Si, and containing, as non-metallic elements, elements selected from one or more of N, C, O, and S and the element B, and the coating containing Si and B has a mixed phase of a crystalline phase and an amorphous phase, the minimum crystal grain size of crystal grains contained in the crystalline phase is set to be 0.5 nm or more and less than 20 nm, such that the toughness of the Si-containing wear-resistant coating is improved by suppressing embrittlement caused by excessive residual compressive stress without sacrificing the high hardness of the Si-containing wear-resistant coating. Furthermore, it is described that substitution of less than 10 at % of the coating components with Cu is effective in improving oxidation resistance.
In addition, Japanese Unexamined Patent Application, First Publication No. 2008-31517 describes a coated tool in which the surface of a tool body is coated with a hard coating layer, and at least one layer of hard coating is expressed by (MaLb)Xc (here, M represents at least one metal element selected from Cr, Al, Ti, Hf, V, Zr, Ta, Mo, W and Y, L represents at least one additional element selected from Mn, Cu, Ni, Co, B, Si, and S, X represents at least one non-metallic element selected from C, N and O, a represents the atomic ratio of M to the sum of M and L, b represents the atomic ratio of L to the sum of M and L, c represents the atomic ratio of X to the sum of M and L, and a, b, and c satisfy 0.85≤a≤0.99, 0.01≤b≤0.15, a+b=1, and 1.00<c≤1.20), whereby crystal grain refinement and crystal stability are achieved by Cu, Si, and the like which are the components of the hard coating, resulting in an increase in high-temperature hardness, an improvement in wear resistance, and furthermore, an improvement in oxidation resistance.
Furthermore, Japanese Unexamined Patent Application, First Publication No. 2008-73800 suggests a coated tool in which a hard coating having a composition Al1-a-b-cSiaMgbMc(BxCyNz) (here, M is at least one element selected from Nb, V, Zr, Cr, Ti, Cu, and Y, and a, b, c, x, y, and z satisfy 0≤a≤0.35, 0≤b≤0.2, 0.03≤a+b≤0.5, and 0≤c≤0.1 in atomic ratio, and 0.9≤Al+Si+Mg, 0≤x≤0.2, 0≤y≤0.4, 0.5≤z≤1, and x+y+z=1 are satisfied in atomic ratio) is formed on the surface of a tool body, thereby improving the hardness, oxidation resistance, toughness, and wear resistance of the hard coating. In addition, it is described that in a case where Cu is contained as a component of the hard coating, an increase in the hardness of the coating due to crystal grain refinement, and a lubricating action are expected.